The text "AEROSOLS: Science and Technology," copyright 1961 by Interscience Publishers, Inc. New York, N.Y., tells the history of the familiar aerosol package which until recently has satisfactorily provided the public with a means for dispensing liquid formulations in the form of a spray having a particle size range small enough to qualify as an aerosol.
That text describes how a liquified compressed gas propellant can pressurize the package with vapor pressures ranging from 15 to 100 psi at 70.degree. C., with the best performance being obtained from the higher pressures; how the propellant flash vaporizes to form an aerosol when ejected through the actuator of the package upon opening its aerosol valve, and how, with some formulations, mechanical breakup actuators can be used, when necessary, to produce an aerosol spray. In addition the use of aerosol valves having vapor taps is described together with information that aerosol valves can be designed like a vapor tap valve but with the tap provided with a normally closed valve which gravitationally opens when the package is used in an inverted position, as disclosed by the Samuel U.S. Pat. No. 2,793,794, May 28, 1957.
After publication of that text, the Samuelson et. al U.S. Pat. No. 3,542,254, issued on Nov. 24, 1970, disclosing an aerosol valve adaptor for a vapor tap aerosol valve and intended to provide for anyway operation of an aerosol package in conjunction with metering of the flow rates of the liquid and vapor components of the package, depending on the position of the package.
Unfortunately, now that the aerosol science and technology has reached a high degree of advancement with full customer acceptance of aerosol packages, these packages have fallen into disrepute because of allegations that fluorocarbon propellants may pollute the stratosphere while the use of hydrocarbon propellants produces packages which are potentially lethal flame throwers by ignition of the spray.
Currently, liquid product manufacturers who have been merchandizing their products in aerosol packages, are turning to manually operated pump packages. A pump dispenser is normally made with a small pump piston area which when the pump is finger operated is consequently capable of pressurizing the liquid product for ejection under high pressures such as those obtained by the liquified gas propellants of aerosol packages; an acceptable spray is then made possible. However, pump-type liquid dispensing packages are more expensive to manufacture and less convenient to use, when compared to the aerosol package.
Squeeze bottle liquid dispensing packages are inexpensive and convenient to use, certainly as compared to the pump-type package and even when compared to the aerosol package.
The problem with squeeze bottles has been that the internal pressure that can be developed by finger pressure to dispense a liquid product by squeezing the squeeze bottle, is much less than can produce a dispensed spray comparable to that provided by aerosol and pump packages using the presently existing science and technology developed in those fields.
Prior art patented proposals are exemplified by the following:
Leong U.S. Pat. No. 1,716,525, June 11, 1929, shows the basic principle used up to date to dispense a spray of liquid droplets via a squeeze bottle. Squeezing of the bottle expels the liquid through an orifice with the air through another orifice, jetting right angularly over the liquid, the mixture ejecting through a dispensing nozzle.
Armour U.S. Pat. No. 2,980,342, Apr. 18, 1961, shows a liquid spray dispensing squeeze bottle package using fundamentally the Leong patent principle modified to permit anyway operation.
Roote U.S. Pat No. 2,981,444, Apr. 25, 1961, for powder and not liquid, but which does propose a squeeze bottle using the basic Leong patent concept and, in addition, the gravity actuated valving and metering of the Samuelson et al. patent.
Lee U.S. Pat. No. 3,493,179, Feb. 3, 1970, proposes a squeeze bottle which to obtain a spray from a liquid content, uses the mechanical breakup concept of the aerosol industry.